Brain imaging: applications in psychiatry

New anatomical and functional imaging methods

Powerful new methods for imaging both brain anatomy and brain function are appearing at an increasing rate. The modern era of minimally invasive, highly informative, neurological diagnostic imaging methods began with the introduction of x-ray computed tomography in the 1970s. More recently, positron emission tomography and single-photon emission computed tomography have been used extensively in research on normal and pathological brain function, and they are finding specific medical applications. Nuclear magnetic resonance methods are in widespread use for neurological diagnosis only a decade after they became available. Rapid development of new techniques based on the same principles, and implementable on clinical instruments with relatively minor modifications, will expand the range of nuclear magnetic resonance measurement capabilities considerably in the near future. These technological innovations and others yet to come have major implications for the practice of neurology. The most important one is an increase in relative value among clinical diagnostic skills of history taking and mental status examination, which will remain largely beyond the reach of technology.

Brain atrophy in hypertension. A volumetric magnetic resonance imaging study

To determine whether hypertension, the predominant risk factor for stroke and vascular dementia, is associated with brain atrophy, magnetic resonance imaging (MRI) scans were performed to quantify brain volumes and cerebrospinal fluid spaces. Eighteen otherwise healthy, cognitively normal older hypertensive men (mean +/- SD age, 69 +/- 8 years, duration of hypertension 10-35 years) and 17 age-matched healthy, normotensive male control subjects were studied in a cross-sectional design. Axial proton-density image slices were analyzed using region-of-interest and segmentation analyses. The hypertensive subjects had significantly larger mean volumes of the right and left lateral ventricles (p less than 0.05, both absolute volume and volume normalized to intracranial volume) and a significantly smaller normalized mean left hemisphere brain volume (p less than 0.05) with a trend toward significance for a smaller normalized mean right hemisphere volume (p less than 0.09). Four hypertensive subjects and one healthy control subject were found to have severe periventricular hyperintensities on T2-weighted MRI images. When data for these subjects were removed from the analyses, the normalized lateral ventricle volumes remained significantly larger in the hypertensive group. Lateral ventricle enlargement was not related to age or use of diuretics in the hypertensive group nor to duration of hypertension between 10 and 24 years. Our findings suggest that long-standing hypertension results in structural changes in the brain. Longitudinal studies will determine whether MRI-associated changes are progressive and if such changes identify hypertensive subjects at increased risk for clinically apparent brain dysfunction.

SPECT imaging in psychiatry. A review

In the last two decades, brain imaging has become an integral part of clinical and research psychiatry. Single photon computed emission tomography (SPECT) is rapidly gaining acceptance as one of the major imaging techniques available, along with computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). Each of these techniques has its assets and drawbacks. This review concerns SPECT, a highly prevalent imaging technique whose potential value in brain imaging has not been appreciated until recently. Its purpose is to expose practicing clinicians and research psychiatrists alike to the attributes of this instrument, which is available in most nuclear medicine departments today. An effort is made to provide a comprehensive account of this technique, including a brief summary of the basic principles, the various methods of its application, and recent findings in most psychiatric disorders. Analogies to its "aristocratic cousin," PET, are presented to emphasize similarities and differences. Finally, directions for future development and implementation of SPECT are suggested.

Comparison of negative symptoms in schizophrenic and poor outcome bipolar patients

Using the Scale for the Assessment of Negative Symptoms (SANS), affective blunting, alogia, and attentional impairment were assessed in 30 manic patients with chronic impairment of inter-episode instrumental functioning and 85 chronic schizophrenic patients. The schizophrenic patients had markedly higher ratings on all three negative symptom dimensions. When negative symptoms were examined categorically, no manic patient was rated to show prominent affective flattening or alogia. This relative specificity may not apply to attentional impairment which was rated as prominent in 17% of the manic patients and in 55% of the schizophrenic patients.

Molecular insights into schizophrenia

A number of studies have demonstrated alterations in the structure and function of the frontal cortex in some schizophrenic patients. The possible etiology and pathogenesis of these abnormalities are unknown, but genetic and developmental causes are frequently mentioned. Recent in vivo 31P NMR studies of the dorsal prefrontal cortex have been conducted in eleven neuroleptic naive, first episode schizophrenic patients and compared with normal controls of comparable age, educational level and parental educational level. The findings in the schizophrenic patients are different from those of normal IQ adult autistic patients of comparable age and Alzheimer's patients but similar to normal elderly controls. These studies show decreased frontal lobe utilization of adenosine triphosphate in the schizophrenic patients which suggests a hypoactive dorsal prefrontal cortex. In addition, indices of membrane phospholipid metabolism are altered in the schizophrenic patients. However, the findings in the schizophrenic patients are quite similar to those observed in normal elderly controls and to those that normally occur to a lesser degree during adolescence. The phospholipid alterations observed in the schizophrenic patients are compatible with either premature aging or altered timing and exaggeration of the regressive events which occur during normal brain development. The changes in high-energy phosphate metabolism observed in the schizophrenic patients may prove to be state dependent, but the changes in membrane phospholipid metabolism could be related to molecular changes that precede the onset of clinical symptoms and brain structural changes in schizophrenia. These findings suggest new avenues of thinking about the pathogenesis and treatment of schizophrenia.

Functional mapping of the human visual cortex by magnetic resonance imaging

Knowledge of regional cerebral hemodynamics has widespread application for both physiological research and clinical assessment because of the well-established interrelation between physiological function, energy metabolism, and localized blood supply. A magnetic resonance technique was developed for quantitative imaging of cerebral hemodynamics, allowing for measurement of regional cerebral blood volume during resting and activated cognitive states. This technique was used to generate the first functional magnetic resonance maps of human task activation, by using a visual stimulus paradigm. During photic stimulation, localized increases in blood volume (32 +/- 10 percent, n = 7 subjects) were detected in the primary visual cortex. Center-of-mass coordinates and linear extents of brain activation within the plane of the calcarine fissure are reported.

Canonical correlation of a temporal lobe signs scale with schizoid and hypomania scales in a normal population: men and women are similar but for different reasons

The relationships between four relevant Minnesota Multiphasic Personality Inventory variables and temporal lobe signs and symptoms were determined separately for 70 university men and 86 women. Canonical correlations were similar in magnitude (0.55 to 0.60) but indicated sex-specific construction of the roots. For men the significant variables were the schizoid and complex partial epileptic-like signs; for women the significant variables were hypomania and all three temporal lobe clusters: complex partial seizure experiences, interictal-like signs, and religious/psi phenomenology.

T1 and T2 relaxation times in schizophrenia as measured with magnetic resonance imaging

T1 and T2 relaxation times were measured in ten brain regions on the right and left side in a sample of 27 schizophrenic patients and 37 normal controls. The schizophrenic patients showed a prolongation of T2 relaxation time, and to a lesser extent of T1 relaxation time, which was more predominantly localized in the right hemisphere and in gray matter structures. These results may indicate that metabolic, physiological, or neurochemical brain function in schizophrenia is related in some way to a change in tissue fluid in neuronal cell bodies or interstitial gray matter.

The role of SPECT brain imaging in assessing psychopathology in the medically ill

Cerebral single photon emission computed tomography (SPECT), a method of functional brain imaging, measures cerebral blood flow and metabolism. This paper describes the imaging procedure and several cases where cerebral SPECT was of use in the differential diagnosis of medically ill patients who also presented with psychopathology. SPECT patterns in cerebrovascular disease, dementia, focal epilepsy, and AIDS are at present the best described and seem to be the most specific. Often changes in regional cerebral blood flow are seen before structural changes become apparent on CT or MRI. Cerebral SPECT can add valuable diagnostic information in assessing psychopathology in the medically ill and can often lead to changes in treatment.

3H-spiperone labels sigma receptors, not dopamine D2 receptors, in rat and human lymphocytes

3H-Spiperone binds to dopamine D2 receptors in striatum and, under the assumption that it labels the same receptors in lymphocytes, this binding site has been suggested as a biological marker for schizophrenia. Recent studies, however, have raised questions about the existence of dopamine receptor changes in drug-free schizophrenic patients, as well as on the presence and/or dopaminergic nature of lymphocytic 3H-spiperone binding sites. In the present study we have conducted an investigation of the binding of 3H-spiperone to rat and human lymphocytes. We found that 3H-spiperone binds in a specific, saturable and reversible manner to a site in lymphocytes; however, its dissociation constant Kd (9 nM) is about 40-fold higher than in striatum. An extensive investigation of the 3H-spiperone sites indicated that their pharmacological profile was not that of a dopamine D2 site, but rather that of sigma receptors, a novel class of non-dopaminergic, non-opioid receptors which bind with high affinity antipsychotic drugs. Sigma receptors were also identified in lymphocytes using the specific ligand 3H-DTG (1,3-di-o-tolyl-guanidine), whose binding characteristics were comparable to those of sigma receptors in rat brain. Receptor density and the pharmacological profile of 3H-spiperone and 3H-DTG were similar. Both compounds also labelled a higher number of sites in B cells than in T cells and a good correlation was found between the lymphocytic binding of both ligands in a group of 58 people. These findings indicate that sigma receptors are present in lymphocytes and suggest that 3H-spiperone binding in these cells occurs to sigma sites and not to dopamine D2 sites.

Left-handedness in male schizophrenic patients is associated with increased impairment on the Luria-Nebraska Neuropsychological Battery

Several studies suggest increased mixed and left-handedness in schizophrenia. This is of interest as early cerebral injury can result in increased left-handedness and some investigations have suggested a role for early developmental insult (e.g., birth complications) in schizophrenia. We administered the Luria-Nebraska Neuropsychological Battery (LNNB) to 24 left-handed male schizophrenic patients and a separate group of 24 right-handed schizophrenic patients who were age and education matched to the left-handed patients. The test protocol also was administered to 15 left-handed non-psychiatric control subjects and 15 right-handed controls. Direct comparisons (t-test) of the left- to right-handed schizophrenics revealed that the left-handed patients showed significantly greater impairment on several LNNB measures sensitive to cognitive deficits in schizophrenia. There were no differences between left- and right-handed control subjects. A further 2 X 2 ANOVA pooling all subjects noted several significant interactions between handedness and diagnostic group. The findings suggest a unique interaction between left-handedness and neuropsychological impairment in schizophrenia and could support a relationship between left-handedness, early cerebral insult, and cognitive deficits.

Cholinergic rebound after chlorpromazine exacerbates lithium muscarinic-induced limbic seizures in rats: implications for psychiatric treatment

When lithium serum levels were within the (human) therapeutic range, young and old adult male and female rats (housed singly or in groups) all displayed faster limbic seizure onset times in response to a muscarinic cholinergic agonist (pilocarpine 20 mg/kg) if a single systemic dosage of chlorpromazine was injected 24 hours previously. The effect was comparable to injecting an additional 10 mg/kg of pilocarpine. These results strongly suggest that cholinergic rebound from chlorpromazine administrations during lithium treatment could facilitate subclinical electrical lability and very localized neuronal necrosis within the limbic system of clinical patients, resulting in normalization of psychiatric symptoms.

Contrast agents and cerebral hemodynamics

Contrast-enhanced magnetic resonance imaging of regional cerebral hemodynamics is discussed. Techniques for measuring cerebral blood volume (CBV) have been validated in animal models and have recently been applied to human studies. Factors affecting CBV measurement in pathologic tissue are addressed. Extension of these techniques to the measurement of cerebral blood flow is presented.

The distinction of positive and negative symptoms. The failure of a two-dimensional model

The distinction of positive and negative symptoms in describing schizophrenic patients has become popular. It presupposes that symptoms cluster in two dimensions, fitting together not only theoretically but empirically. Factor analysis of three published studies of 93, 62 and 52 schizophrenic patients and a large pooled sample showed that more than two distinct dimensions are required to categorise symptoms in schizophrenia. This result is consistent across methods and samples, and with previous literature. The added dimensionality resulted from a splitting of the positive symptom domain into more distinct factors.

Functional studies of the human brain using high-speed magnetic resonance imaging

Dramatic technical advances in magnetic resonance imaging (MRI or NMR) scanning speed and recent governmental approval for the routine use of NMR contrast agents have yielded techniques for quantitative imaging of cerebral hemodynamics. The technical basis of ultrafast imaging, the methodology of dynamic imaging with contrast agents, and results in normal subjects and patients are presented.

Functional brain imaging in the evaluation of psychiatric illness

In the past century, the field of psychiatry has undergone major changes. During this time, significant advancements in both diagnosis and treatment have occurred. Medical brain imaging using structural and functional brain imaging techniques have contributed, in part, to a better basic understanding of psychiatric disease and to an improving diagnostic approach. Computed tomography and magnetic resonance imaging have supplied limited, but useful insight regarding structural alterations in schizophrenia and the affective disorders. Position emission tomography imaging has already made a major contribution in the assessment of schizophrenia and affective disorders. Single-photon emission computed tomography (SPECT), which is currently more widely available, should contribute more to psychiatric disease evaluation in the future. Recent advances in SPECT technology in the areas of improved instrumentation--such as multidetector and ring detector systems and new radiopharmaceuticals including new rCBF markers and receptor site imaging agents--have contributed to significant improvements in the SPECT imaging technique. At the present time, SPECT has been shown to be feasible and useful in the evaluation of acute and chronic psychiatric and demented states. As SPECT technology continues to evolve, further refinements in this diagnostic capability can be anticipated.

Age-related changes in the relative growth of the posterior fossa

We have established a normative data set for the relative size of the structures of the midline posterior fossa from birth to 90 years old. Data were obtained from morphometric analysis of midsagittal magnetic resonance imaging scans of the brain utilizing a simple image analysis system. There are several significant changes in the size of these structures with an increase in chronologic age. The relative size of the cisterna magna decreases with age. Anterior cerebellar vermal lobules (I through V) appear to grow more rapidly than the rest of the cerebellum. Other, less significant, trends include a decrease in the overall size of the cerebellum, superior posterior vermal lobules (VI and VII) and inferior posterior lobule (VIII) with an increase in age. It is, therefore, necessary to use age-standardized normative data when making morphometric correlations with clinical disorders.

Positron emission tomography in the investigation of neuropsychiatric disorders: update and comparison with magnetic resonance imaging and computerized tomography

In many neuropsychiatric disorders, PET imaging offers functional insights unavailable from anatomic imaging alone. Functional deficits may be more extensive than structural findings would indicate, may occur before the detection of anatomic changes, or may even occur in the absence of any structural lesions. We contrast the current role of PET with that of MRI and CT in the investigation of neuropsychiatric disorders including stroke, tumor, head trauma, epilepsy, schizophrenia, movement disorders, normal aging and dementia.

Regional brain metabolism during auditory hallucinations in chronic schizophrenia

Regions of the brain involved in language and attention were studied using [18F]-fluorodeoxy-glucose in PET. In nine chronic DSM-III schizophrenic patients who had persistent auditory hallucinations, ten who had recovered from hallucinations and ten normal controls. In none of the regions examined was metabolic activity significantly different in hallucinating patients compared with that in other groups. However, a pattern of seven significant correlations of metabolic activity between language regions and between frontal and parietal cortex characterised the hallucinating but not the other groups. Three of the seven correlations were significantly greater in hallucinating patients than in the two other groups, and six were greater in hallucinating patients than controls. Metabolism in Broca's region and its right-hemisphere homologue correlated positively and significantly in the hallucinating group, as it did in anterior cingulate and left superior temporal areas, and in right frontal and parietal areas. Hallucination ratings correlated with metabolism in the anterior cingulate region.

Functional cerebral imaging by susceptibility-contrast NMR

In vivo measurement of cerebral physiology by dynamic contrast-enhanced NMR is demonstrated. Time-resolved images of the cerebral transit of paramagnetic contrast agent were acquired using a new ultrafast NMR imaging technique and a novel mechanism of image contrast based on microscopic changes in tissue magnetic susceptibility. Global hypercapnia in dogs was used to establish the relationship between susceptibility-induced signal change and brain blood volume, and the response of gray and white matter to this microvascular stimulus was measured.

Psychophysiology at the interface of clinical science, cognitive science, and neuroscience

Research in schizophrenia illustrates that the field of psychophysiology lies at the interface of clinical science, cognitive science, and neuroscience. Electrodermal abnormalities in schizophrenic patients have been found reliably across laboratories, and data reported here demonstrate that these abnormalities are at least partially dependent upon the clinical state of the patients. Both tonic and phasic electrodermal activity increased when schizophrenic patients entered into a psychotic episode, and preliminary evidence suggests that the increases may serve as early prodromal signs of an impending episode. Significance of the electrodermal abnormalities for understanding cognitive and attentional deficits is suggested by associations with secondary reaction time and startle blink probe findings. Neuroscience implications are highlighted by the correlation of the electrodermal abnormalities with regional brain metabolic activity indexed by positron emission tomography. An important task for the future is to interrelate measures from these various domains. The field of psychophysiology is particularly well positioned for this task.

Sight and insight: regional cerebral metabolic activity in schizophrenia visualised by positron emission tomography, and competing neurodevelopmental perspectives

Over the past several years there has emerged a family of highly sophisticated but technically complex procedures for the visualisation of a range of cerebral functions in living man (Andreasen, 1988). The images they produce are so beguiling not just because of their potential to give new insights into the pathophysiology and treatment of major psychiatric disorders, but because they convey information through a quite fundamental modality: people are only convinced by what they can see. However, initial applications of such new technology have appeared just as likely to generate new questions and contradictions as to provide answers to current issues. This is readily illustrated by recent studies on the imaging of brain dopamine receptors in schizophrenic patients by positron emission tomography (PET) (see Waddington, 1989a).

Neuroimaging and affective disorder in late life: a review

Within the past two decades brain imaging techniques have given the clinician access to new anatomical and functional findings for dealing with affective disorder in the older age group. Despite the proliferation of such technology, the significance of findings on computerized axial tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) remains unclear in this patient group. The literature covering old age depression and imaging techniques is reviewed, and problems related to methodology, sample selection, and implications for the direction of future research are discussed. Current evidence particularly suggests that subcortical atrophy may be an important factor in the genesis of affective disorder in old age. The question of cognitive decline in the setting of affective disorder is examined. The use of brain imaging techniques may have particular bearing upon identification of etiology of affective disorder, prediction of treatment response, or risk of relapse.

Magnetic resonance imaging in clinical psychiatry

Although psychiatric researchers have been quick to adopt magnetic resonance imaging (MRI) of the brain in their investigations, its clinical application has been slow to develop and most psychiatrists remain unaware of its potential advantages and disadvantages compared with CT scanning. In this article the procedures are compared and the potential advantages of MRI highlighted with the help of neuropsychiatric case histories. Clinical situations are then discussed in which a psychiatrist should consider ordering a MRI scan subsequent to or instead of a CT scan.

Enlargement of cerebral third ventricle in psychotic patients with delayed response to neuroleptics

Enlargement of the cerebral third ventricle appears to be a replicable finding in groups of patients with psychotic illnesses, and there is evidence for an association of third ventricle enlargement with poorer response to treatment. Third ventricle area and width were measured from computed tomography (CT) scans in 24 mood-incongruent psychotic patients and 14 controls age and gender matched to schizophrenic patients. Patients were treated with a fixed dose of haloperidol and classified as rapid responders (55% symptom reduction on New Haven Schizophrenic Index (NHSI) within 4.5 +/- 1.3 days) or delayed responders (55% symptom reduction on NHSI within 18.6 +/- 10.5 days). The significant enlargement of third ventricle area was isolated among the 12 delayed neuroleptic responders (19.3 +/- 9.0 mm2) compared with the 14 controls (11.7 +/- 4.8 mm2, p = 0.01), and 12 other mood-incongruent psychotics. Third ventricle width also showed a trend towards larger width in the delayed responders. There was a clear positive correlation between ventricular size and patient's age exclusively in the delayed responders (r = 0.78); a comparable relationship between ventricular size and age was not present in controls, or in the other psychotics. This finding is consistent with an age-related progressive degenerative process in the central nervous system (CNS) isolated to the neuroleptic-delayed responsive psychotics.

Reduced temporal lobe areas in schizophrenia: preliminary evidences from a controlled multiplanar magnetic resonance imaging study

Seventeen young patients with relapsing schizophrenia and 13 normal controls matched for age, gender, and educational level underwent magnetic resonance imaging (MRI) scans. Three sagittal, eight axial, and seven coronal images were obtained for all subjects. Schizophrenic patients showed a reduction of brain tissue in the temporal lobes. Among the several brain structures identified, left temporal lobe area, but not ventricular brain ratio (VBR), discriminated between the two groups. As VBR has been reported to be increased in the more severe forms of schizophrenia, temporal lobe abnormalities may characterize the less severe cases of schizophrenia.

Biological psychiatry: is there any other kind?

It has been my custom as Head of the Department of Psychiatry at Washington University to interview as many as possible of the medical students applying for positions in our residency training programme. I typically ask the candidates how they decided to apply to us, what they know about our programme, and what they have heard from others about our department. The answers to these questions have been interesting and informative to me and have characteristically provided a good basis for the discussions that followed, designed to help us decide about the applicants and, equally important, to help the applicants decide about us.

Clinical applications of SPECT

The clinical use of single photon emission computed tomography (SPECT) has grown steadily over the last decade. SPECT is now an essential technique for certain studies such as cerebral blood flow imaging. Many other common nuclear medicine studies give better results when they are performed with SPECT. These include myocardial perfusion imaging with thallium-201 or the new technetium-99m perfusion agents, myocardial infarct imaging with infarct-avid agents, imaging of tumors or infections with agents such as gallium-67 or indium-111 WBC's, and certain cases of bone imaging. Still other studies such as liver/spleen imaging, most brain studies, and perhaps renal imaging may benefit from SPECT even though planar imaging gives satisfactory results. Future developments in 3D display techniques and faster computers may extend the clinical usefulness of SPECT to other areas such as pulmonary perfusion imaging and gated cardiac blood pool imaging.

Topographic mapping of EEG and evoked potentials in psychiatry: delusions, illusions, and realities

This paper reviews the utility of topographic mapping of EEG and evoked potentials in psychiatry. Further, a wide variety of caveats related to this technique are reviewed including cerebral and extracerebral sources of artifact. Moreover, both questionable and legitimate uses of mapping in psychiatry are addressed and possible future applications of this technique are considered. Finally, multidisciplinary approaches to the study of the brain are discussed.